1. Field of the Invention
This invention relates to a data recording system, particularly to a data recording system for recording data indicative of the operating state of an apparatus such a vehicle.
2. Description of the Related Art
Japanese Laid-open Patent Application No. Hei 6(1994)-18293, for example, teaches a technology related to such a data recording system. When the data recording system set out in this publication transfers measured data temporarily stored in a ring buffer to a prescribed recording region where it is stored, it ordinarily simultaneously thins the data at prescribed time interval. When the measured data falls outside a prescribed range, the data recording system generates a trigger and the stored data are transferred to and recorded at the prescribed recording region without thinning before and after trigger generation.
When the data recorded by such a data recording system are used to analyze the cause of an apparatus or equipment abnormality, the occurrence of an abnormality in the subject apparatus can defined as the condition for trigger generation.
Preferably, the data recording system should be capable of recording data related to apparatus abnormalities and failures in prescribed recording regions separately by type. That said, it must be noted, however, that apparatus abnormalities are of two types, transient and continuous. Transient abnormalities are ones likely to disappear of their own accord over the course of time, e.g., ones caused by noise and appearing only temporarily and ones appearing transiently under special operating states such as during extremely high-load operation. In other words, transient abnormalities are ones likely to shift repeatedly between normal and abnormal states (ones having high repeatability). These are called xe2x80x9cabnormalitiesxe2x80x9d in this specification. Continuous abnormalities are persistent ones unlikely to disappear of their own accord and low in repeatability. These are called xe2x80x9cfailuresxe2x80x9d in this specification. Transient abnormalities generally reappear a number of times. Therefore, if the occurrence of an abnormality is defined as the condition for generating a trigger, data on the same kind of abnormality will be recorded multiple times. As this wastes recording region capacity, it may become impossible to record important data on other abnormalities and failures.
One conceivable way of overcoming this problem would be to carefully discriminate whether an abnormality is a transient abnormality or a failure and when it is determined to be a failure to generate the aforesaid trigger and record data. With this configuration, however, it would be impossible to record data on transient abnormalities.
In troubleshooting apparatus abnormalities and failures, data for a prescribed period before the occurrence of the abnormalities (including ones which may later be determined to be failures), particularly data including information on the period of transition from the normal state to the abnormality (failure) state, are generally more important than data acquired before the occurrence of the abnormality or failure. Still, a certain amount of time is ordinarily required to determine that an apparatus abnormality is a failure. An inconvenience has therefore existed in that after an apparatus abnormality was determined to be a failure, data for a prescribed period prior to the abnormality (failure) needed to analyze (troubleshoot) the cause of the abnormality (failure) could no longer be obtained.
This inconvenience can be eliminated by continuously recording data over a period extending from a prescribed time point prior to abnormality (failure) occurrence to the time that the abnormality is determined to be a failure. However, since this results in also recording data that arise after the occurrence of the abnormality or failure and are not particularly essential for troubleshooting, i.e., data for the period during which the abnormality is determined to be a failure, it does not solve the problem of wasted recording region capacity.
Moreover, in view of the importance of the transition period data, recording of low repeatability data (i.e., of transition periods whose type is not likely to recur) associated with failures should be given priority to recording of high repeatability data (i.e., of transition periods whose type is likely to recur) associated with transient abnormalities.
An object of the present invention is therefore to provide a data recording system that overcomes the foregoing problems and enables important data related to a diversity of abnormalities and failures to be efficiently recorded in a prescribed recording region.
In a first aspect, the present invention achieves the foregoing object by providing a system for recording data indicative of operating condition of an apparatus, comprising; abnormality detecting means for detecting abnormality in the data; abnormality type discriminating means for discriminating a type of the abnormality when the abnormality is detected; record checking means for checking whether the data has been recorded in a prescribed recording region in association with the discriminated type of the abnormality; and data recording means for recording the data in the prescribed recording region in association with the discriminated type of the abnormality, when the data has not been recorded in the prescribed recording region in association with the discriminated type of the abnormality.
In a second aspect, the present invention achieves the foregoing object by providing a system for recording data indicative of operating condition of an apparatus, comprising; abnormality detecting means for detecting abnormality in the data; data recording means for recording the data in a prescribed recording region successively when the abnormality is detected; apparatus failure determining means for determining the abnormality as a failure of the apparatus based on a prescribed condition, when the abnormality is detected; and data erasing means for erasing the data when it is determined at a prescribed time point that the abnormality has not been determined as the failure of the apparatus.